Background: The Indianapolis VA and Indiana Health Information Exchange (IHIE) will partner through the VLER HEALTH program to perform bi-directional health information exchange (HIE). The VA-IHIE program will deliver the outside electronic health records of Veterans who opt-in to the program to their VA and non-VA providers at the point of care when they are seen. Little is known empirically about the effect of HIE upon health care quality and cost. Aim 1: to assess the proportion and predictors of health care received by Veterans outside the VA Aim 2: to assess the impact of VA-IHIE upon the quality of care received by Veterans Hypothesis 1: implementation of VA-IHIE will improve the quality of ambulatory care among Veterans Hypothesis 2: implementation of VA-IHIE will reduce admission rates for ambulatory care sensitive conditions among Veterans Hypothesis 3: implementation of VA-IHIE will reduce overuse of medical tests among Veterans Aim 3: to explore whether the implementation of VA-IHIE will reduce the economic expenditures of health care for Veterans Study Population: Our study population is Veteran patients who have been seen at both the Indianapolis VA and a non-VA medical institution associated with IHIE and, thus, have health care information to exchange. In the implementation group, the VA-IHIE program will be delivered to 2,000 Veteran patients who have been seen at the Indianapolis VA in the past 15 months. The control group will include Veterans with additional health care data outside the VA, for whom information exchange has not been activated. Study Design: A pre-post evaluation of the VA-IHIE implementation, with a concurrent control group, will be performed among Veterans seen at the Indianapolis VA. We will use a propensity score approach to mimic randomization since the patients will not be randomized to VA-IHIE activation due to implementation constraints. Data on care received by Veterans will be obtained for one year before, and one year after, VA-IHIE enrollment. Data will be drawn from VA and IHIE electronic health record information. Measures: We will measure the impact of HIE upon health care quality in terms of both the (1) underuse of ambulatory care services and (2) overuse of medical tests. Given that overuse measures are generally underdeveloped, we will convene a set of expert panels to facilitate the development of a set of overuse measures. Finally, we will measure economic expenditures before and after VA-IHIE implementation. We will measure potential covariates that may affect the impact of VA-IHIE based upon our conceptual framework. These factors include VA-IHIE access (or HIE transactions), provider interdependence (utilization), and patient complexity (sociodemographic characteristics, diseases, and comorbidity), as well the amount and type of clinical data available outside the VA.